XRT72L13 Datasheet, PDF (288/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
áç
PRELIMINARY
TX DS3 F-BIT MASK2 REGISTER, ADDRESS = 0X37
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
FBit Mask(23) FBit Mask(22) FBit Mask(21) FBit Mask(20) FBit Mask(19) FBit Mask(18) FBit Mask(17) FBit Mask(16)
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
TX DS3 F-BIT MASK3 REGISTER, ADDRESS = 0X38
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
FBit Mask(15) FBit Mask(14) FBit Mask(13) FBit Mask(12) FBit Mask(11) FBit Mask(10) FBit Mask(9) FBit Mask(8)
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
TX DS3 F-BIT MASK4 REGISTER, ADDRESS = 0X39
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT2
BIT 1
BIT 0
FBit Mask(7) FBit Mask(6) FBit Mask(5) FBit Mask(4) FBit Mask(3) FBit Mask(2) FBit Mask(1) FBit Mask(0)
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
4.2.5 The Transmit DS3 Line Interface Block
The XRT72L13 Framer IC is a digital device that
takes DS3 payload and overhead bit information from
some terminal equipment, processes this data and ul-
timately, multiplexes this information into a series of
"outbound" DS3 frames. However, for DS3 coaxial
cable applications, the XRT72L13 Framer IC lacks
the current drive capability to be able to directly trans-
mit this DS3 data stream through some transformer-
coupled coax cable with enough signal strength for it
to comply with the Isolated Pulse Template require-
ments and be received by the remote receiver.
Therefore, in order to get around this problem, the
Framer IC requires the use of an LIU (Line Interface
Unit) IC. An LIU is a device that has sufficient drive
capability, along with the necessary pulse-shaping
circuitry to be able to transmit a signal through the
transmission medium in a manner that it can (1) com-
ply with the DSX-3 Isolated Pulse Template require-
ments and (2) be reliably received by the Remote Ter-
minal Equipment. Figure 84 presents a circuit draw-
ing depicting the Framer IC interfacing to an LIU
(XRT7300 DS3/E3/STS-1 Transmit LIU).
276